Ectopic pleural thymoma with T-cell lymphocytosis and bone metastasis: a case report.

BACKGROUND: The diagnostic complexities that arise in radiographic distinction between ectopic pleural thymoma and other thoracic neoplasms are substantial, with instances of co-occurring T-cell lymphocytosis and osseous metastasis being exceedingly rare. CASE PRESENTATION: A 51-year-old woman was admitted to our hospital with dyspnea and chest pain. Upon imaging examination, she was found to have diffuse and nodular pleural thickening on the left side, collapse of the left lung and a compression in the second thoracic vertebrae. All lesions showed significant 18F-FDG uptake on 18F-FDG PET/CT examination. Furthermore, she exhibited T-cell lymphocytosis in her peripheral blood, lymph nodes, and bone marrow. After ruling out malignant pleural mesothelioma (MPM), lung cancer with pleural metastasis, and T-cell lymphoma, the definitive diagnosis asserted was ectopic pleural thymoma with T-cell lymphocytosis and bone metastasis. CONCLUSION: Physicians need to expand their knowledge of the imaging features of ectopic pleural thymoma. Cases with T-cell lymphocytosis may exhibit increased aggressiveness and prone to bone metastasis.

Presumed pseudo-Pelger-Huët anomaly and basophilia secondary to chronic lymphocytic leukemia in a dog.

A 10-year-old neutered male Maltese dog was presented for an investigation of lymphocytosis. The dog was up-to-date on vaccinations and deworming. Physical examination did not reveal any significant abnormalities. A complete blood cell count (CBC) showed mild leukocytosis with moderate lymphocytosis, basophilia, and moderate neutropenia, but no significant left shift or toxic change. Serum biochemistry and urinalysis were unremarkable. All performed tests for infectious agents common in this geographical region were negative. No significant abnormalities were found on abdominal ultrasound examination. Multiparametric flow cytometry of peripheral blood showed a CD8+ T-cell lymphocytosis, and PCR for antigen receptor rearrangement revealed a clonal expansion of the T-cell receptor gamma chain genes. A clinical diagnosis of chronic lymphocytic leukemia (CLL) was made, and follow-up was recommended. On Day 48 post-presentation, the CBC showed mild non-regenerative anemia (NRA), moderate leucocytosis due to moderate to marked lymphocytosis, basophilia, and a marked increase in hyposegmented neutrophils with mild toxic change in the absence of neutrophilia or neutropenia. Treatment with chlorambucil and prednisolone was initiated. On Days 87 and 197 post-presentation, the CBC showed mild NRA, with progressively decreasing numbers of hyposegmented neutrophils. The dog remained without clinical signs. Basophilia and probable pseudo-Pelger-Huët anomaly were possibly secondary to CLL. To the authors' knowledge, this is the first report of these two hematologic conditions secondary to CLL in dogs. Recognition of a pseudo-Pelger-Huët anomaly is clinically relevant to avoid misinterpretation as a marked left shift due to severe inflammation and prevent unnecessary urgent therapeutic actions.

[Persistent Polyclonal B-Cell Lymphocytosis (PPBL): An Entity That Is Not What it Seems]. / Linfocitose Policlonal Persistente de Células B (LPPB): Uma Entidade que Não É o que Parece.

Persistent polyclonal B-cell lymphocytosis is a rare disease with chronic lymphocytosis of polyclonal origin, which is more frequent in mostly asymptomatic middle-aged female smokers. The hallmark of this entity is the presence of bilobed/binucleated B lymphocytes, which are polyclonal as demonstrated by immunophenotyping; an elevated IgM level is common. This disease shows, in most cases, an indolent course over many years and, although controversial, it may rarely convert to malignant lymphoma. In addition to smoking, a genetic predisposition for persistent polyclonal B-cell lymphocytosis is likely. Recurrent genetic aberrations have been described. The differential diagnosis includes non-Hodgkin's lymphoma and a clear distinction between both entities is of the utmost importance because treatment is generally not indicated in the former: instead, regular follow-up is recommended. The authors describe the case of a 46-year-old female smoker, who presented with chronic lymphocytosis, elevated IgM and circulating binucleated lymphocytes. Excluding lymphoma was important considering the unusual presentation with constitutional symptoms and splenomegaly.

A linfocitose policlonal persistente de células B é uma doença rara, caracterizada por linfocitose crónica policlonal, que ocorre mais frequentemente em mulheres fumadoras de meia-idade, que se apresentam assintomáticas ou com sintomas inespecíficos. A presença de linfócitos B binucleados é considerada a assinatura citomorfológica desta entidade. A imunofenotipagem comprova a sua origem policlonal, observando-se muitas vezes uma elevação da IgM sérica. É controverso se existe um risco aumentado de desenvolvimento de linfoma. A predisposição genética é também um fator de risco, além do tabagismo. Apesar da sua natureza policlonal, alterações genéticas recorrentes estão descritas. Na linfocitose policlonal persistente de células B a abordagem terapêutica consiste habitualmente numa vigilância regular, o que reforça a importância do seu reconhecimento. Os autores descrevem o caso de uma mulher de 46 anos, fumadora, com linfocitose crónica, IgM elevada e linfócitos binucleados. O diagnóstico diferencial com linfoma assumiu particular importância, considerando os sintomas constitucionais e esplenomegalia que apresentava.

A tower of babel of acronyms? The shadowlands of MGUS/MBL/CHIP/TCUS.

With the advent of outperforming and massive laboratory tools, such as multiparameter flow cytometry and next-generation sequencing, hematopoietic cell clones with putative abnormalities for a variety of blood malignancies have been appreciated in otherwise healthy individuals. These conditions do not fulfill the criteria of their presumed cancer counterparts, and thus have been recognized as their precursor states. This is the case of monoclonal gammopathy of unknown significance (MGUS), the first blood premalignancy state described, preceding multiple myeloma (MM) or Waldenström macroglobulinemia (WM). However, in the last 2 decades, an increasing list of clonopathies has been recognized, including monoclonal B cell lymphocytosis (MBL), which antecedes chronic lymphocytic leukemia (CLL), clonal hematopoiesis of indeterminate potential (CHIP) for myeloid neoplasms (MN), and T-cell clones of uncertain significance (TCUS) for T-cell large chronic lymphocytic leukemia (LGLL). While for some of these entities diagnostic boundaries are precisely set, for others these are yet to be fully defined. Moreover, despite mostly considered of "uncertain significance," they have not only appeared to predispose to malignancy, but also to be capable of provoking set of immunological and cardiovascular complications that may require specialized management. The clinical implications of the aberrant clones, together with the extensive knowledge generated on the pathogenetic events driving their evolution, raises the question whether earlier interventions may alter the natural history of the disease. Herein, we review this Tower of Babel of acronyms pinpointing diagnostic definitions, differential diagnosis, and the role of genomic profiling of these precursor states, as well as potential interventional strategies.

TOX as a new diagnostic marker for T cell large granular lymphocytic leukaemia.

AIMS: T cell large granular lymphocytic leukaemia (T-LGLL) is a rare disorder that may underlie otherwise unexplained cytopenias. The identification of T-LGLL cells in bone marrow biopsies can be a challenge, because a robust immunohistochemistry marker is lacking. The markers currently in use (granzyme B, TIA-1 and CD8) are difficult to interpret or lack specificity. Therefore, we investigated whether immunohistochemistry for thymocyte selection-associated high-mobility group box (TOX), a transcription factor that associates with chronic T cell stimulation, could be a reliable tool for the identification of T-LGLL cells. METHODS AND RESULTS: In this retrospective study, expression of TOX in CD8+ cells in bone marrow biopsies of T-LGLL patients (n = 38) was investigated and compared to bone marrow of controls with reactive T cell lymphocytosis (n = 10). All biopsies were evaluated for TOX staining within the CD8-positive T cell population. The controls were essentially negative for TOX, whereas all T-LGLL cases were positive (median = 80%, range = 10-100%), even when bone marrow involvement was subtle. CONCLUSION: TOX is a highly sensitive marker for the neoplastic cells of T-LGLL and we recommend its use, especially in the diagnostic work-up of patients with unexplained cytopenias.

Characterization of Three Somatic Mutations in the 3'UTR of RRAS2 and Their Inverse Correlation with Lymphocytosis in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by progressive accumulation of a rare population of CD5+ B-lymphocytes in peripheral blood, bone marrow, and lymphoid tissues. CLL exhibits remarkable clinical heterogeneity, with some patients presenting with indolent disease and others progressing rapidly to aggressive CLL. The significant heterogeneity of CLL underscores the importance of identifying novel prognostic markers. Recently, the RAS-related gene RRAS2 has emerged as both a driver oncogene and a potential marker for CLL progression, with higher RRAS2 expression associated with poorer disease prognosis. Although missense somatic mutations in the coding sequence of RRAS2 have not been described in CLL, this study reports the frequent detection of three somatic mutations in the 3' untranslated region (3'UTR) affecting positions +26, +53, and +180 downstream of the stop codon in the mRNA. An inverse relationship was observed between these three somatic mutations and RRAS2 mRNA expression, which correlated with lower blood lymphocytosis. These findings highlight the importance of RRAS2 overexpression in CLL development and prognosis and point to somatic mutations in its 3'UTR as novel mechanistic clues. Our results may contribute to the development of targeted therapeutic strategies and improved risk stratification for CLL patients.

B-cell leukemia in an adult sheep.

B-cell leukemia is a rare form of hematologic neoplasia in sheep, especially in adult animals. We present a case report of a 5-year-old WhiteFace Sheep wether with suspected acute lymphoblastic leukemia. The patient, a second-generation relative of ewes experimentally inoculated with atypical scrapie, exhibited acute lethargy and loss of appetite. Laboratory investigation revealed marked leukocytosis, lymphocytosis, and abnormal serum chemistry panel results. Microscopic examination of blood and bone marrow smears exhibited a high percentage of large neoplastic cells with lymphoid characteristics. Histopathologic analysis of the spleen, liver, lungs, and other organs confirmed the presence of widespread tissue infiltration by neoplastic cells. Immunohistochemical labeling demonstrated strong intracytoplasmic labeling for CD20, consistent with B-cell neoplasia. Flow cytometric analysis confirmed the B-cell lineage of the neoplastic cells. Screening for bovine leukemia virus, which can experimentally cause leukemia in sheep, yielded a negative result. In this case, the diagnosis of B-cell leukemia was supported by a comprehensive panel of diagnostic evaluations, including cytology, histopathology, immunohistochemistry, and immunophenotyping. This case report highlights the significance of accurate diagnosis and classification of hematologic neoplasia in sheep, emphasizing the need for immunophenotyping to aid in the diagnosis of B-cell leukemia. It also emphasizes the importance of considering spontaneous leukemia as a differential diagnosis in sheep with lymphoid neoplasia, especially in the absence of circulating infectious diseases.

Clinico-Haematological Profile Of Chronic Lymphoproliferative Disorders In Patients Presenting With Lymphocytosis.

Objectives: To assess the spectrum and clinico-haematological profile of chronic lymphoproliferative disorders in patients presenting with lymphocytosis. METHODS: The cross-sectional, retrospective study was conducted at the Aga Khan University Hospital, Karachi, and comprised data related to cases of bone marrow aspirate and trephine from January to November 2020. Patients for whom the bone marrow was done for lymphocytosis were studied for the presence of lymphoproliferative disorders, sub-types and patients'characteristics. The diagnosis and classification were based on the World Health Organisation criteria for tumours of haematopoietic and lymphoid tissues. Data was analysed using SPSS 21. RESULTS: Of the 3,334 bone marrow specimenstested, 103(3%) were related to lymphocytosis. Of these, 84(82%) were diagnosed with lymphoproliferative disorders, while diagnosisremained undetermined in 19(18%) cases. Male:female ratio was 3.6:1 and median age was 60 years (range: 21-85 years). Constitutional symptoms were found in 61(73%) patients. Median absolute lymphocyte count was 45x109/L (range: 5.3-480). All 84(100%) patients were classified as B-cell lymphoproliferative disorder. Chronic lymphocytic leukaemia wasthe most common form, 61(73%), and 31(51%) of them presented with advanced stage disease. CONCLUSIONS: A huge majority of patients presenting with lymphocytosis had underlying lymphoproliferative disorders of which B-cell chronic lymphocytic leukaemia was found to be the most common.

Differential diagnosis of lymphocytosis in routine laboratory practice: Contribution of lymphocyte parameters using the Sysmex-XN9000 haematology analyzer.

INTRODUCTION: This study investigates the potential contribution of structural and dispersion parameters, as well as alarms provided by Sysmex XN9000 haematology analyzer. The objective was to assess the need for a microscopic examination in the context of lymphocytosis. It also aims to contribute in differentiating rapidly lymphoproliferative disorders such as chronic lymphocytic leukaemia (CLL), non-chronic lymphocytic leukaemia (NON-CLL) and non-infectious reactive lymphocytosis (REAC). METHODS: We prospectively assessed lymphocyte parameters (Ly-X, Ly-Y, Ly-Z, Ly-WX, Ly-WY, Ly-WZ) provided by the Sysmex XN9000 analyzer; they were measured in the white blood cell differential (WDF) channel which also provides alarms via the precursor/pathological cellular channel (WPC). Blood samples from 71 subjects with CLL, NON-CLL lymphoproliferative and REAC non-infectious reactive lymphocytosis, as well as a control (NORM) group of 12 subjects without any abnormalities were analyzed. RESULTS: The most discriminating parameters to distinguish the different groups were Ly-X, Ly-Z and Ly-WZ. The lymphoid structural parameters Ly-X and Ly-Z significantly discriminated the CLL group from the other groups (p < 0.001), and the CLL group from the REAC group (p < 0.01), respectively. The Ly-WZ parameter discriminated the CLL group from the NON-CLL, REAC (p < 0.001) and NORM (p < 0.01) groups. Alarms were higher in all study groups compared to the NORM group. An algorithm integrating these structural and alarm parameters is proposed. CONCLUSION: This study demonstrated that Ly-X, Ly-Z, and Ly-WZ lymphocyte parameters are useful for detecting morphological changes in lymphocytes; they provide useful information for the differential diagnosis of lymphocytosis, and this before the examination of the blood smear. An algorithm combining the WDF (parameters) and the WPC (alarms) makes it possible to decide whether or not to use a microscopic examination or flow cytometry immunophenotyping.

Intestinal Epithelial Digestive, Transport, and Barrier Protein Expression Is Increased in Environmental Enteric Dysfunction.

Environmental enteric dysfunction (EED) is characterized by malabsorption and diarrhea that result in irreversible deficits in physical and intellectual growth. We sought to define the expression of transport and tight junction proteins by quantitative analysis of duodenal biopsies from patients with EED. Biopsies from Pakistani children with confirmed EED diagnoses were compared to those from age-matched North American healthy controls, patients with celiac disease, and patients with nonceliac disease with villous atrophy or intraepithelial lymphocytosis. Expression of brush border digestive and transport proteins and paracellular (tight junction) proteins was assessed by quantitative multiplex immunofluorescence microscopy. EED was characterized by partial villous atrophy and marked intraepithelial lymphocytosis. Epithelial proliferation and enteroendocrine, tuft, and Paneth cell numbers were unchanged, but there was significant goblet cell expansion in EED biopsies. Expression of proteins involved in nutrient and water absorption and that of the basolateral Cl- transport protein NKCC1 were also increased in EED. Finally, the barrier-forming tight junction protein claudin-4 (CLDN4) was significantly upregulated in EED, particularly within villous enterocytes. In contrast, expression of CFTR, CLDN2, CLDN15, JAM-A, occludin, ZO-1, and E-cadherin was unchanged. Upregulation of a barrier-forming tight junction protein and brush border and basolateral membrane proteins that support nutrient and water transport in EED is paradoxical, as their increased expression would be expected to be correlated with increased intestinal barrier function and enhanced absorption, respectively. These data suggest that EED activates adaptive intestinal epithelial responses to enhance nutrient absorption but that these changes are insufficient to restore health.

T-Cell Prolymphocytic Leukemia With t(X;14)(q28;q11.2): A Clinicopathologic Study of 15 Cases.

OBJECTIVES: T-cell prolymphocytic leukemia (T-PLL) is a rare mature T-cell leukemia usually characterized by inv(14)(q11.2q32)/t(14;14)(q11.2;q32). In this study, we aimed to investigate the clinicopathologic features and molecular profile of T-PLL associated with t(X;14)(q28;q11.2). METHODS: The study group included 10 women and 5 men with a median age of 64 years. All 15 patients had a diagnosis of T-PLL with t(X;14)(q28;q11.2). RESULTS: All 15 patients had lymphocytosis at initial diagnosis. Morphologically, the leukemic cells had features of prolymphocytes in 11 patients, small cell variant in 3, and cerebriform variant in 1. All 15 patients had hypercellular bone marrow with an interstitial infiltrate in 12 (80%) cases. By flow cytometry, the leukemic cells were surface CD3+/CD5+/CD7+/CD26+/CD52+/TCR α/ß+ in 15 (100%) cases, CD2+ in 14 (93%) cases, CD4+/CD8+ in 8 (53%) cases, CD4+/CD8- in 6 (40%) cases, and CD4-/CD8 + in 1 (7%) case. At the cytogenetic level, complex karyotypes with t(X;14)(q28;q11.2) were seen in all 15 patients assessed. Mutational analysis showed mutations of JAK3 in 5 of 6 and STAT5B p.N642H in 2 of 6 patients. Patients received variable treatments, including 12 with alemtuzumab. After a median follow-up of 17.2 months, 8 of 15 (53%) patients died. CONCLUSIONS: T-PLL with t(X;14)(q28;q11.2) frequently shows a complex karyotype and mutations involving JAK/STAT pathway, and it is an aggressive disease with a poor outcome.

Expansion of large granular lymphocytes after autologous hematopoietic stem cell transplantation.

Expansion of large granular lymphocytes (LGLs) is sometimes observed in allogeneic hematopoietic stem cell transplantation (HSCT) recipients, and is reported to be associated with a favorable transplant outcome. LGLs are also observed after autologous HSCT, but their clinical implications have not been well investigated. We retrospectively reviewed peripheral blood smears of consecutive autologous HSCT recipients. LGL lymphocytosis was defined as the observation of LGLs in the peripheral blood (> 20% white blood cells) in at least two consecutive blood tests. We evaluated the clinical impact of LGL lymphocytosis on autologous HSCT recipients. LGL lymphocytosis was observed in 18 of 197 patients (9.1%) who received autologous HSCT, at a median of 49 days after transplantation, with a median duration of 120.5 days. Incidence of cytomegalovirus reactivation was significantly higher in patients with LGL lymphocytosis than those without (16.7% vs. 3.3%, p = 0.038). No significant difference in survival rates was observed between groups (3 year OS 90.9% vs. 90.5%, p = 0.793 for lymphoma; 100 vs. 92.4%, p = 0.328 for myeloma). LGL lymphocytosis was observed in almost 10% of autologous HSCT recipients. In contrast to allogeneic HSCT, the duration of LGL was shorter and no significant improvement in survival was observed.

From the archives of MD Anderson Cancer Center: Aleukemic T-prolymphocytic leukemia, a rare presentation and review of the literature.

T-prolymphocytic leukemia (T-PLL) is a rare, aggressive T-cell leukemia, and patients typically present with marked peripheral blood lymphocytosis. Approximately 15-20 % of patients may present with moderate and relative stable lymphocytosis and an indolent clinical course that can persist for a few years. However, eventually these patients go on to develop marked lymphocytosis and rapidly progressive disease. We report a 72-year-old man who presented with multicompartmental lymphadenopathy and a normal complete blood count. Excision of left and right cervical lymph nodes showed replacement of the lymph node architecture by a small T-cell neoplasm positive for CD3, CD4, CD5, CD7 and TCL-1, and negative for CD8, CD20, CD30 and ALK. Subsequent bone marrow evaluation showed minimal bone marrow involvement by a T-cell neoplasm associated with TCL1A rearrangement in 11 % of cells supporting the diagnosis of T-PLL. Despite treatment, he showed progressive lymphadenopathy while remarkably maintaining normal white blood cell counts until he eventually developed leukocytosis of 110.9 × 103/uL 26 months later. Review of the literature identified only a single abstract reporting a patient with a similar lymphoma-like presentation and normal white blood cell count; however, that case showed significant bone marrow involvement in stark contrast to the current case. In summary, we report a highly unusual case of T-PLL can initially presenting with an aleukemic or lymphoma-like clinical picture, which can make establishing the diagnosis challenging.

Dasatinib-induced spleen contraction leads to transient lymphocytosis.

The tyrosine kinase inhibitor dasatinib is approved for Philadelphia chromosome-positive leukemia, including chronic myeloid leukemia (CML). Although effective and well tolerated, patients typically exhibit a transient lymphocytosis after dasatinib uptake. To date, the underlying physiological process linking dasatinib to lymphocytosis remains unknown. Here, we used a small rodent model to examine the mechanism of dasatinib-induced lymphocytosis, focusing on lymphocyte trafficking into and out of secondary lymphoid organs. Our data indicate that lymphocyte homing to lymph nodes and spleen remained unaffected by dasatinib treatment. In contrast, dasatinib promoted lymphocyte egress from spleen with kinetics consistent with the observed lymphocytosis. Unexpectedly, dasatinib-induced lymphocyte egress occurred independently of canonical sphingosine-1-phosphate-mediated egress signals; instead, dasatinib treatment led to a decrease in spleen size, concomitant with increased splenic stromal cell contractility, as measured by myosin light chain phosphorylation. Accordingly, dasatinib-induced lymphocytosis was partially reversed by pharmacological inhibition of the contraction-promoting factor Rho-rho associated kinase. Finally, we uncovered a decrease in spleen size in patients with CML who showed lymphocytosis immediately after dasatinib treatment, and this reduction was proportional to the magnitude of lymphocytosis and dasatinib plasma levels. In summary, our work provides evidence that dasatinib-induced lymphocytosis is a consequence of drug-induced contractility of splenic stromal cells.

Extreme lymphocytosis in a dog with T-zone lymphoma.

Background: Canine T-zone lymphoma (TZL) is recognized as an indolent CD45-T cell lymphoma, with low aggressiveness and high overall survival. The diagnosis is obtained by histopathology and immunohistochemistry, but also by cytological examination of the lymph node associated with immunophenotyping. Lymphocytosis is commonly identified as around 10,000 cells/µl and may reach 30,760 cells/µl. Case Description: The present report describes a case of a female Golden Retriever, nine years old, with generalized lymphadenopathy. In the cytological examination of the superficial cervical lymph node, a monomorphic population of small, "clear cells" and "hand mirror" lymphocyte shape was suggestive of TZL. The leukogram showed intense leukocytosis (160,050 cells/µl) due to small clear cell lymphocytosis (152,048 cells/µl). The myelogram showed a myeloid:erythroid ratio of 2:3; with a pyramidal distribution of cell types and the presence of 22.8% of lymphocytes in the differential count. Bone marrow, peripheral blood, and lymph node immunophenotyping resulted in lymphocyte gates with 97.3% to 99.5% CD5+, predominantly CD4-, CD8-, and CD45- confirming the diagnosis of TZL with associated leukemia. Treatment with chlorambucil and prednisolone was started. During the first month, the lymphocytosis remained above 200,000 cells/uL. After four months of treatment, there was a decrease in lymphocytes, which progressively reached a count of 10,800 cells/ul in the eleventh month. Conclusion: In the literature, lymphocytosis above 30,760 cells/µl has not been observed in TZLs. Thus, it is believed that this is the first report of extreme lymphocytosis with a slow response to chemotherapy.

[Splenic lymphoma, diagnosis and treatment]. / Lymphomes spléniques : diagnostic et prise en charge.

Some common clinical situations, such as splenomegaly or lymphocytosis, or less common, such as autoimmune hemolytic anemia, cold agglutinin disease, or cryoglobulinemia can lead to the diagnosis of splenic lymphoma. Splenic lymphoma is rare, mainly of non-hodgkinian origin, encompassing very different hematological entities in their clinical and biological presentation from an aggressive form such as hepato-splenic lymphoma to indolent B-cell lymphoma not requiring treatment such as marginal zone lymphoma, the most frequent form of splenic lymphoma. These entities can be challenging to diagnose and differentiate. This review presents different clinical and biological manifestations suspicious of splenic lymphoma and proposes a diagnosis work-up. We extended the strict definition of splenic lymphoma (lymphoma exclusively involving the spleen) to lymphoma thant can be revealed by a splenomegaly and we discuss the differential diagnosis of splenomegaly.

Monoclonal B-cell lymphocytosis in the bone marrow: revisiting the criteria for chronic lymphocytic leukemia/small lymphocytic lymphoma.

Monoclonal B-cell lymphocytosis is a clonal B-cell population in the peripheral blood (PB) of <5x10ˆ9/L without extramedullary (EM) disease, often with a chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) phenotype. The degree of bone marrow (BM) involvement is not currently a part of the diagnostic criteria for MBL or CLL/SLL, but CLL-type MBLs in BM can be seen in patients lacking PB lymphocytosis. Data are limited on the outcome of such cases. We assessed the clinicopathologic characteristics of isolated BM CLL-type MBL in patients who did not meet criteria for CLL/SLL. We evaluated BMs from 2006 to 2018 with CLL-like clonal B-cell populations in patients with a PB absolute lymphocyte count or monoclonal B-cell count of <5 × 109/L and without definite evidence of EM disease. We investigated the extent and pattern of marrow involvement, PB counts, flow cytometric data, genetics, concurrent hematopoietic diseases, and outcomes including progression and treatment. Thirty cases with BM MBL but <5x10E9/L PB monoclonal B cells and no EM disease were identified. Thirteen of 30 had additional hematopoietic neoplasms. The mean patient age was 74.1 years (median: 77 years, range: 43-91 years). No patients had lymphadenopathy (LAD) or splenomegaly by physical examination. By imaging, nine of 18 had LAD (8/9 < 1.5 cm) and four of 18 had splenomegaly but with other attributable etiologies. Mean PB absolute lymphocyte count (ALC) was 1.8×10E9/L (range: 0.5-5.0×10E9/L). Twenty-four of 30 (80%) had low-level (<20%) BM involvement by MBL, and among these, none with available follow-up data progressed to diagnostic CLL/SLL. Six of 30 (20%) had >20% marrow involvement by MBL. Four of 6 were treated for CLL/SLL due to cytopenias, despite not meeting diagnostic criteria, and all 4 were CD38 or ZAP70 positive and had cytogenetic abnormalities, including trisomy 12. One of 6 developed overt CLL/SLL 3 years later and had cytogenetic abnormalities at the time of MBL diagnosis. One of 6 was monitored without treatment but had no cytogenetic abnormalities.Isolated BM CLL-type MBL represents a diagnostic gray area, and this study highlights the range of clinical outcomes. All cases with <20% BM involvement did not require CLL-specific treatment or progress to CLL/SLL. In the 4 cases where treatment was initiated due to cytopenias, patients had ≥20% BM involvement, CD38 or ZAP70 expression, and cytogenetic abnormalities but lacked a PB ALC of ≥5x10E9/L or LAD ≥1.5 cm, suggesting that not all patients with clinically significant disease will meet criteria for CLL/SLL. The results also show that concurrent hematopoietic disorders can complicate the diagnosis, as the disease course or treatment may result in leukopenia, precluding PB absolute lymphocytosis. Though larger studies are needed, the degree of BM involvement, in conjunction with flow cytometric prognostic markers, and cytogenetic abnormalities may be a useful addition to the current diagnostic criteria for CLL/SLL which only considers a PB numerical cutoff and EM involvement.

Bronchoalveolar lavage lymphocytosis in hypersensitivity pneumonitis: a retrospective cohort analysis with elimination of incorporation bias.

BACKGROUND: Recent studies support the diagnostic role of bronchoalveolar lavage lymphocytosis (BALL) in patients with suspected hypersensitivity pneumonitis (HP). Our study aim was to determine the spectrum of BALL findings with elimination of incorporation bias in non-fibrotic and fibrotic patients and assess correlates of positive BALL cut-off and BALL association with long-term outcomes in those with fibrotic disease (f-HP). METHODS: A single-center retrospective cohort study was pursued of patients undergoing diagnostic bronchoscopy for interstitial lung disease. Strict study enrollment was based on recent ATS/JRS/ALAT diagnostic guidance meeting 'moderate' or higher diagnostic confidence. BALL findings were assessed in both fibrotic and non-fibrotic HP patients with regression and survival analysis pursued for correlates of positive BALL cut-off and long-term outcome. RESULTS: A total of 148 patients (88 fibrotic and 60 non-fibrotic) meeting moderate or higher diagnostic confidence were included. Median BALL in f-HP was 15% compared to 19% in non-fibrotic patients, with only 28% of f-HP meeting diagnostic cut-off (≥ 30%) compared to 41% of non-fibrotic. For f-HP, centrilobular nodules on computed tomography was positively correlated with a diagnostic BALL (OR 4.07; p = 0.018) while honeycombing was negatively correlated (OR 6.9 × e-8; p = 0.001). Higher BALL was also associated with lower all-cause mortality (HR 0.98; p = 0.015). CONCLUSION: With elimination of incorporation bias, most patients with well-described HP did not meet diagnostic BALL thresholds. Higher BALL was associated with better long-term survival in those with fibrosis, but its diagnostic role may be more additive than characteristic or distinguishing.

Development of Monoclonal B-cell Lymphocytosis Shortly After Treatment with Nivolumab and Subsequent Progression to Chronic Lymphocytic Leukemia.

INTRODUCTION: Immune checkpoint inhibitors, such as programmed death (PD)-1 inhibitor nivolumab, are currently widely used in treatment of various malignancies. Due to their widespread application, any new potential adverse effects due to these agents necessitate careful assessment. CASE REPORT: We report a case of an 81-year-old man with recurrent high-risk malignant melanoma who underwent a 12-month adjuvant treatment with nivolumab. Shortly after the course of nivolumab, he developed monoclonal B-cell lymphocytosis (MBL) which subsequently progressed to chronic lymphocytic leukemia (CLL). MANAGEMENT AND OUTCOME: The patient is currently doing clinically well in Rai stage 0. Malignant melanoma remains in remission. CONCLUSION: Considering the pathophysiologic plausibility of nivolumab inducing B-cell dysregulation via PD-1 inhibition, we suggest further studies on potential association between nivolumab and B-cell malignancies.